Grinding-mill.



Patented Mar. I9, |90I.'

No. smns,

T. L. L T. .L sTulTEvANT.'

GRINDING MILL.

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No. 670.,"6. l Patented Mar. |9,'|9o|. T. L. a T. J.KsTumEvANT.

GRINDING MILL.

. (Application filed Jan. 30, 1900.' (N o M o d e l L) 'mi mums msn: o0mofouno.. wnmuammac rUnirrnn Sterns anion..

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THOMAS LEGGETT STURTEVANT, OF QUINOY, AND THOMAS JOSEPH STURTEVANT, OFNEWTON CENTER, MASSACHUSETTS.

cammino-MILL.

SPEGEIEXCATION forming part or" Letters Patent N0. 670,116, dated March19, 1901.

Application filed January 30, 1900. Serial No. 3,289. (No model.)

To all whom t may concern.'

Be it known that we, THOMAS LEGGETT STURTEvANT,residingat Q uinoy,in thecounty of Norfolk, and THOMAS JOSEPH STURTE- VANT,residing at New tonOenter,in the county of Middlesex, State of Massachusetts, citizens ofthe United States, have invented certain new and useful Improvements inGrinding- Mills, of which the following is a specification, referencebeing had therein to the accompanying drawings.

Our invention relates to grinding-mills or pulverizers, and particularlythat type in which rotating grinding instrumentalitiessuch asgrinding-disks, rotary beaters or disks, and interposedcrushing-ballS-are used to crush or pulverize the material.

The particular features of grinding-mills to which our invention relatesare the feeding and screening agencies used in connection with thegrinding instrumentalities, and they are shown in the present case asapplied to a grinding-mill of the vertical-disk type, although it willbe understood that we do not limit ourselves to their use with thespecific form of mill herein shown, as our invention is applicable toother types and constructions of rotary grinding or crushing mills.

ln the drawings accompanying and forming a part of this specification,Figure 1 is a central vertical longitudinal section of a vertical-diskgrinding-mill of the well-known Sturtevant Rock Emery type on line l lof Fig. 2 looking in the direction of the arrows. Fig. 2 is a transversesection of the sam e, taken on the line 2 2 of Fig. 1. Fig. 3 is a viewin elevation of the front head of the mill-casing to show the return-feed chute; and Fig. 4 is a detail view of one of the`returnfeedcarriers, the stop projection cooperating therewith being shown indotted lines in operative relation thereto.

Referring to the drawings by numerals, like numerals indicating likeparts throughout the several views, 1 indicates the base or bed of themill, provided with suitable bearings 2, in which is mounted ahorizontally-arranged shaft 3, provided with a driving-pulley 4..Secured t'o said shaftso as to rotate therewith is a runner stone ordisk 5, said runner-stone or its supporting-disk being provided at itsperiphery with a series of Scrapers or carriers 6, to which referencewill be made hereinafter. Opposed to said runner-stone is the bed-stone7, which is iixedly mounted in the mill-case, the runner-stone 5 beingforced against said bed-stone 7 with a yielding pressure by means of thespring 8, mounted in the end bearing or box 2, so as to give alongitudinal thrust to the runnerstone shaft 3. The grinding-disks 5 and7 are provided with the usual central eye 8, through which the materialto be ground passes to the grinding-stones, said shaft 3 beingpreferably provided with a feed-screw 9, which projects slightly beyondthe hedstone 7, and receiving the material to be ground as it falls fromthe hopper carries it through the feed-eye 8 to the bosom of the stones.Surroundingthesaid grinding-stones is a casing 10, said casingsupporting the main hopper 11 and havinga front plate 12, provided withan opening 13, which is connected with the hopper ll by means of a chute14, a stirring device 15 being preferably mounted in the throat of thehopper to prevent clogging of the material. The bed-stone 7 ispreferably suitably attached to the said front plate 12. On the innerface of said front plate 12 is an auxiliary hopper or trough 16, whichdirects the material fed in from the hopper ll to the feed-screw 9, saidauxiliary hopper 16 having a wide flaring mouth.

The casing l0 is provided at one side with a discharge-opening 17, asclearly shown in Fig. 2, and which discharge-opening communicates withthe chamber of an inclined screen box or casing 1S, which is outside ofthe mill-casing l0 and in which is mounted an inclined screen 19, saidscreen being preferably tangentially lplaced relative to the circularcasing 10 and to the path of movement ofthe grinding-disk 5 and the pathof movement of the carriers 6, rotating with said disk, the box orscreen casing 18 having a discharge-spout 2l at its lower end. The boxor casing i8, partly broken away in Fig. 2, is closed at its upper endto prevent escape of the material projected into the chamber thereof andalso to prevent any air-blast or suction therethrough. Thedischarge-opening 17 and screen-box 1S are located on the up IOOwardly-running side of the grinding-disk or grinding device.

The inclined screen 19 is located at a distance from and is thus whollyindependent of the feeddulet of the mill-casing, so thatit is notsubjected to wear b y the incoming coarse or unreduced material.

As the crushed material is discharged from the grinding-disks it iscaught by the revolving carriers 6, and is thus given a circularmovement. The tendency of the material is ofcourse to leave the casingrat a tangent, and when the crushed material swept along by the carriers6 reaches the discharge or screen opening 17 it is by centrifugal forcethrown tangentially through said opening into the chamber of the screenbox or casing 1S and in such a manner that it will mainly strike againstthe inclined closed upper side of said box or casing and be deilectedagainst or fall on the inclined screen 19 in the said screen-box atsharp angles to said screen, and in any event but little or none of thematerial will be thrown directly on the said screen by the rotatingparts of the mill. The material being thus discharged vupon the screenat sharp angles thereto will first have a tendency to travel upwardslightly on said screen, and then owing to gravity and thejarring actionof the machine it will slide down the inclined screen, and that portionof the material which passes through the screen will be discharged atthe spout 21, while the tailings or coarser portions of the materialwill in the form of mill herein shown be returned to the mill-casing.

It is well known that with a given mesh of screen a much finer output issecured when the material is sifted by being passed down an inclinedscreen than when the material is sifted by being discharged directlyupon the screen at or about a right angle to the latter, so that ourinclined screen, upon which the material is discharged tangentially,will enable us to secure a fine output with a comparatively coarse-wirescreen, which is much stronger and which will withstand much more wearthan a line-mesh screen would. A further and very important advantagesecured by locating the screen outside of and at an inclination to themill and the grinding agencies is that such screen is not subjected tothe wear and tear of the moving mass of ground and unground material, aswould be the case were the screen located within the mill-casing andnot, as shown,in a box independent thereof and communicating therewiththrough a tangential discharge-opening, so that only the ground and fineproducts pass through the discharge-opening and fall upon the screen. Asa result of this arrangement the life of the screen is prolonged, andmeans for protecting the screen from the destructive action of therapidly-moving mass of material within the mill-casing may bedispensedwith. Again,thescreenbeinginclined tangentially to the path ofmovement of the material under treatment does not have to withstand thedirect impact of the ground material, which is being` carried around bythe pulverizing means and projected through the discharge-opening; butthe material to be screened is thrown into the screen-box and spends itsforce both by reason of its tangen tial Hight and its impact against theinclined upper side of the inclined screen-box, so that it will bedeflected upon the screen, and thus is not forcibly projected againstthe screen by the rotating parts of the mill, but only strikes thescreen when its force is spent and then mostly at sharp angles.

The coarse material returned by the screen to the mill-casing will hetaken up again by the rotating carriers 6 and owing to the inclinedarrangement of the faces of said carriers will be gradually workedtoward the right, Fig. 1, until it is discharged from the ends of saidcarriers into the auxiliary hopper 1G, whence it passes to the eye ofthe stones and is fed in ward to be reground bythe revolving feed-screw9. The lateral movement of the material and discharge of the same at thetop of the millcasing is assisted by the stop projection 23, with whichthe interior of the casing is preferably provided and which, opposingthe rotating movement of the material with the carriers, has a tendencyto cause the material to travel laterally and also causes it to bedeflected downward, so as to be discharged into the auxiliary hopper 9.

The rotating carriers (i, as herein shown, are formed tapering, asillustrated in the detail view Fig. 4t, for the purpose of provid ingthe same with inclined faces for working the material laterally. It willbe understood, however, that a mere inclined arrangement of saidrotatingl carriers on the runner-stone would effect the same result.

One of the advantages of a mill provided with an inclined screen such isabove dcscribed, and shown in the drawings, is, as has already beensuggested, that a much heavier screen for securing a given output may beused and one capable of withstanding greater wear than the screeningarrangements now in use in mills of this type, it having been found thatan inclined screen of substantially twenty mesh to the lineal inch,arranged as shown and described, will give an output as tine as a screenof forty mesh where the mate rial is thrown against the screen atrightangles thereto. A further advantage of the inclined screen arranged asshown is that it will return the unreduced material to the mill-casingfor further pnlverization.

The combination of carriers and returnfeed which cooperate in carryingthe unground products to the grinding agencies for further reductioninsures the grinding of the material to the desired degree of iineness,for it will be seen that the only discharge from the mill is thrhugh thescreen-box feed-dis- IOO charge spout 21 out, of Which the lnaterialpasses after it has gone through the meshes of the screen, and suchmaterial as is not ground to a suiiicient degree of iineness to passthrough the meshes of the screen will be returned to Irhe mill to beagain subjected to the action of the grinding devices.

We do not wish to be understood as limiting' our invention to theparticular kind of grinding-mill With vertically-placed grinding-disksherein shown, as our inclined screen located outside of the mill-casingand upon which the material is thrown by centrifugal force may be usedeither with or without means for returning the tailings to the mill tobe reground and in connection with any grinding` or reducinginstrumentalities adapted to throw the crushed material onto theinclined screen by centrifugal action.

There is great advantage in the arrangement herein shown and describedof ascreen outside of the mill-case, in that a screen thus arranged isnot exposed to the rough usage to which it Would necessarily besubjected if arranged Within the mill-case.

So far as we are aware all attempts heretofore made to use line screensin the cases of mills have been more or less unsuccessful for the reasonthat such screens could not stand the wear and tear to which they arenecessarily exposed when thus arranged, While our present arrangement ofthe screen outside of the mill-case permits the use of a comparativelyfine screen without liability of injury to the same.

Having thus described our invention, we claim and desire to secure byLetters Patent- 1. In a pulverizing or grinding mill, the combinationwith a mill-casing having a feedinlet and a discharge-opening, ofrotating reducing means Within said mill-casing, an inclined screen boxor casing located outside the said mill-casing and on theupwardly-running side of said rotating reducing means, said screen boxor casing having a closed upper end and an inclined upper side againstwhich latter the material is mainly projected by the rotating parts ofthe mill, the chamber of said screen-box communicating with the chamberof said mill-casing through said discharge-opening, and an inclinedscreen in said screen-box which receives the reduced material deflectedfrom the upper side of the screen-box, and which inclined screen is at adistance from and is thus independent of the said feed-inlet to themill-casing, so that it is not subjected to wear by the incoming coarseor unreduced material.

2. ln a pulverizing or grinding mill, the combination with a mill-casinghaving a feedinlet and a discharge-opening, of rotating reducing meanswithin said mill-casing, an inclined screen box or casing locatedoutside of said mill-casing and on the upwardly-running side of saidrotating reducing means, said screen-box having a closed upper end andan inclined Lipper side against which latter the material is mainlyprojected by the rotating parts of the mill, the chamber of saidscreenbox communicating with the chamber of said mill-casing throughsaid discharge-opening, an inclined screen in said screen-box whichreceives the reduced material deflected from the upper side of thescreen-box, and which inclined screen is at a distance from and is thusindependent of the said feed-inlet to the mill-casing, so that it is notsubjected to Wear by the incoming coarse or unreduced material, androtating means, independent of said screen, for returning the tailingsdischarged by said screen into the mill-casing to the reducing devicesto be regrouud.

3. In a pulverizing or grinding mill, the combination with amill-casing, having a feedinlet and a discharge-opening, of rotatinggrinding means within said mill-casing, revolving Scrapers or carriers,an inclined screen box or casing located outside of said mill-casing andon the upwardly-running side of said rotating reducing means, saidscreenbox havinga closed upperend and a closed upper side, the chamberof said screen-box communicating with the chamber of said millcasingthrough said discharge-opening, and an inclined screen in saidscreen-box which receives the material projected into the chamber of thescreen-box by the rotating devices of the mill and first mainly thrownby said rotating devices against the closed upper side of the saidscreen-box, said inclined screen being located at a distance from andbeing thus independent of said feed-inlet to said mill-casing so that itis not subjected to -Wear by the incoming coarse or unreduced material.

4. In a pulverizing or grinding mill, the combination with the casingthereof, and a rotating reducing device in said casing, of roratingscrapers or carriers, an inclined screen located outside of said casingand upon which the material is thrown by the said rotating Scrapers orcarriers, and independent stal-ionary means, within said casing, forcausing the screen rejections or tailings to be discharged from saidrotating carriers at or near the top of the casing and to bereturned tothe reducing device to be reground.

5. In a pulverizing or grinding mill, the combination with a mill-casinghaving a feedinlet and a discharge-opening, of reducing means rotatingin a vertical plane within said mill-casing, an inclined screen box orcasing outside said mill-casing and the chamber of which communicateswith the chamber of said mill-casing through said discharge-opening,said screen-box having a closed upper end and an inclined closed upperside, and said box being located on the upwardly-running side of saidrotating reducing means, so that the reduced material projected into thechamber of said casing by the rotating parts IOO IIO

of the mill strikes mainly against said inclined upper side of said box,and an inclined screen in said screen-casing which receives the reducedmaterial thrown into the chamber of said casing aft-er it has beendeflected from the said inclined upper side of said screen-box, saidinclined screen being located at a distance from and being thusindependent of said feed-inlet to said mill-casing so that it is notsubjected to Wear by the incoming coarse or unreduced material.

6. In a pulverizing or grinding mill, the combination with the casingthereof, and a rotating reducing device within said casing, of a screenlocated outside of said casing and upon which the reduced material isthrown by centrifugal action, and rotating carriers located Within saidcasing and having their acting faces inclined relative to their plane ofaction, and stationary means, as stop projection 23, within said casing,and cooperating with said rotating carriers to Work the materiallaterally, and means, also Within said casing, for returning the unreduced material discharged from said carriers to the reducing devices tobe reground.

7. In a pulverizing or grinding mill, the combination with the casingthereof, and rotating grinding means Within said casing, of an inclinedscreen located outside of said casing and arranged to return thetailings from said screen to the chamber of said casing to be regrouud,rot-ating carriers within said casing for raising the screen rejectionsor tailings to, or near to, the top of the latter, an auxiliary hopperwithin said casing into which the screen rejections or tailings aredischarged from said carriers, and means for feeding the material fromsaid auxiliary hopper to the grinding devices.

8. In a pulverizing or grinding mill, the combination With a mill-casinghaving a feedinlet and a discharge-opening, of a fixed bedstone mountedin said casing in a vertical position, a horizontal shaft, avertically-placed runner-stone carried by said shaft and coperating withsaid bed-stone, a screen box or casing outside said mill-casing and thechamber of which communicates with the chamber of said mill-casingthrough said dischargeopening, said screen-box having a closed upper endand a closed upper side against Which latter the reduced materialprojected into the chamber of said screen-box by the rotating parts ofthe mill is mainly thrown, and an inclined screen in said screen-boxwhich finally receives the reduced material projected into the chamberof said box, said inclined screen being located at a distance from andbeing thus independent of said feed-inlet to said mill-casing so that itis not subjected to Wear by the incoming coarse or unreduced material.

9. In a pulverizing or grinding mill, the combination with the casingthereof, of a bedstone fixedly mounted within said casing in a verticalposition, a horizontal shaft, a vertically-disposed runner-stone carriedby said shaft, an inclined screen-casing located outside of saidmill-casing and having a closed upper end, an inclined screen housed insaid screen-casing and upon which the reduced material is indirectlythrown by centrifugal action, and carriers rotating with saidrunner-stone and serving to throw the reduced material onto the saidscreen as also to carry the screen rejections or tailings upward in saidcasing to be returned to the grinding devices to be reground.

l0. In a pulverizing or grinding mill, the

combination with the casing thereof, of vertically-placed bed and runnerstones, the latter of which rotates in a vertical plane, of an inclinedscreen-box having a closed upperend and located outside of the saidmill-casing and the chamber of which box communicates with the chamberof said mill-casing, an inclined screen Within said box and arranged toreturn its tailings to said mill-casing, a dischargespout below saidscreen for the egress of the reduced material,rotating carriers Withinsaid casing for assisting in the return of the screen rejections ortailings to the grinding devices, and means, cooperating with saidcarriers, for feeding the returned material to the grindingstones.

11. In a pulverizing or grinding mill, the combination with the casingthereof, and rotating reducing means within said casing, of ascreen-casing located outside of said millcasing and having a closedupper end, an inclined screen housed within said screen-casing, and uponwhich' the reduced material is indirectly thrown by centrifugal action,said screen being so arranged as to return its tailings to the chamberof said millcasing, rotating Scrapers or carriers for lifting the screenrejections or tailings in said mill-casing, means, coperating with saidcarriers, for feeding the returned material to the reducing device to beregrouud, the said mill-casin g being provided at its upper portion withstationary means for deflecting the material lifted by said Scraperslaterally and downward to assist in its return to the reducing device.

l2. In a pulverizing or grinding mill, the combination witha mill-casinghaving a feedinlet and a discharge-opening, of rotating reducing meanswithin said millcasing, a screen box or casing located outside saidmillcasing and on the upwardly-running side of said rotating reducingmeans, said screen box or casing having a closed upper end and beingalso closed on its side toward the said mill-casing, the chamber of saidscreen box or casing communicating with the chamber of said mill-casingthrough said dischargeopening, an inclined screen in said screen box orcasing and which screen receives and IOC IIO

screens the material thrown outward from the screen,for carrying thetailings to the rotating said mill-casing by the rotating parts of thereducing means. mill, said inclined screen being located at a Intestimony whereof We afx our signadistance from and being thusindependent of tures in the presence of two Witnesses. 5 said feed-inletto said mill-casing so that it is not subjected to Wear by the incomingcoarse or unrednced material, and said screen also being arranged toreturn the tailings to Witnesses: the said mill-casing to be furtherreduced, LLOYD MAKEPEACE,

zo and rotating devices, independent of said L. H. STURTEVANT.

